Cancer is the second leading cause of death in the United States (U.S.), with higher incidence and mortality rates for African Americans than other racial or ethnic groups. Studies suggest that oxidative stress may be causally related to the incidence of many chronic diseases, such as cancer, and that antioxidant nutritional status is inversely related to the occurrence of various cancers. However, there is limited information about possible racial differences in associations between antioxidant nutrients and oxidative stress in healthy persons, and there is a need for improved methodologies to accurately assess self-reported antioxidant nutrient intakes in population-based epidemiologic studies. The hypothesis of this project is that African Americans have lower blood levels of antioxidant nutrients and higher levels of oxidative stress than Whites, which may be one reason why African Americans have higher rates of cancer. The specific aims are to 1) determine whether dietary estimates and blood levels of antioxidant nutrients (total carotenoids, beta-carotene, lycopene, vitamin C, and vitamin E) and oxidative stress (measured as oxidative DNA damage in peripheral lymphocytes) differ between healthy African Americans and Whites, 2) examine associations between antioxidant nutrient status and oxidative DNA damage, by race, and 3) develop and test the relative validity era new antioxidant nutrient questionnaire by comparison to 4-day food records and nutrient biomarkers, and examine whether the validity differs between African Americans and Whites. To accomplish these aims, we will recruit a sample of 150 healthy (i.e., cancer and other chronic disease-free) male and female adults (75 African American and 75 White), age 20-45 years, from the Research Triangle Area of North Carolina. All participants will complete the new antioxidant nutrient questionnaire, a demographic and health questionnaire, a 4-day food record, and have blood samples collected for evaluation of antioxidant nutrients (carotenoids, vitamin C, and vitamin E levels) and oxidative DNA damage using the single cell gel electrophoresis or alkaline Comet assay. This project fills an important gap in antioxidant and cancer research by providing important information about biological relationships between antioxidant nutrients and oxidative stress in a mixed-race sample, with applications to cancer risk. In addition, this work would potentially provide investigators with a validated instrument for assessing antioxidant nutrient exposure in population-based studies in the U.S.